Pluggable join framework for stream processing

ABSTRACT

Disclosed are embodiments for providing batch performance using a stream processor. In one embodiment, a method is disclosed comprising receiving an event, such as a streaming event, from a client. The method determines that the event comprises a primary event and, if so, writes the primary event to a cache and returning the primary event to the client. The method later receives a second event from the client, the second event associated with the first event, annotates the second event based on the primary event, and returns the annotated second event to the client.

COPYRIGHT NOTICE

This application includes material that may be subject to copyrightprotection. The copyright owner has no objection to the facsimilereproduction by anyone of the patent disclosure, as it appears in thePatent and Trademark Office files or records, but otherwise reserves allcopyright rights whatsoever.

BACKGROUND

In the era of big data processing, data pipelines have become vital toingesting, processing, and outputting large quantities of data at highvelocity and having high variability. In general, a data pipelinecomprises a series of automated processing stages that take raw inputdata and convert the raw input data into a more suitable format forconsumption by downstream computer processing systems.

Various architectures of data pipelines exist, including batch, Lambda,and Kappa architectures. Batch data pipelines process data in “batches”at regular intervals and are suitable for non-critical functionalitywhile providing high reliability of data processing. Batch datapipelines, however, suffer from not being able to process data inreal-time. Thus, a lag behind the ingestion of data and output of usefulinformation or knowledge always exists in a batch data pipeline.

Lambda pipelines utilize a batch processor concurrently with a streamprocessor. In these pipelines, the batch processor processes all datawithin a historical batch while the stream processor “augments” theprocessed batch data with the results of stream processing. Eventually,the batch processor will “re-process” the data processed by the streamprocessor and overwrite the information generated by the streamprocessor. Lambda pipelines are fast, due to the use of streamprocessors; however, they require duplication of processing logic inboth the stream processors and the batch processors. Further, Lambdapipelines use twice the processing hardware due to the use of twoseparate processing paradigms (i.e., stream and batch, which process thedata in the same manner).

Like Lambda pipelines, Kappa pipelines utilize a stream processor.However, Kappa pipelines eschew a batch processor. Kappa pipelinesrequire frequent “re-running” of event streams through the streamprocessor to provide simulated batch performance. Kappa pipelines ensurethat streaming data is processed correctly (e.g., the pipeline does notdrop or duplicate data); however, these pipelines ensure this byre-executing processing and are thus slower than pure streamingpipelines. Further, since Kappa pipelines use stream processingtechniques, there is no method for performing more complex operationssuch as joins or aggregations, since these operations inherently requireaccess to a full (e.g., batch) dataset. That is, stream processorsinherently cannot perform these operations, thus replaying streams doesnot remedy this problem.

BRIEF SUMMARY

This disclosure recognizes a need in the art for a new pipelinearchitecture that provides the advantages of stream processors (e.g.,speed) with the advantages of batch processors (e.g., integrity andcomplex operations). The disclosed embodiments provide these advantagesand solve other problems in existing pipelines.

The disclosed embodiments describe an improved big data processingsystem that uses a stream processing engine with additional hardware andsoftware to harden inaccuracies detected during stream processing.

In one embodiment, a method is disclosed comprising receiving a firstevent from a client, the first event comprising a streaming event;determining that the first event comprises a primary event; writing thefirst event to a cache and returning the first event to the client;receiving a second event from the client, the second event associatedwith the first event; annotating the second event based on the firstevent; and returning the annotated second event to the client.

In another embodiment, an apparatus is disclosed comprising a processor;and a storage medium for tangibly storing thereon program logic forexecution by the processor, the stored program logic causing theprocessor to perform the operations of: receiving a first event from aclient, the first event comprising a streaming event; determining thatthe first event comprises a primary event; writing the first event to acache and returning the first event to the client; receiving a secondevent from the client, the second event associated with the first event;annotating the second event based on the first event; and returning theannotated second event to the client.

In another embodiment, a non-transitory computer-readable storage mediumfor tangibly storing computer program instructions capable of beingexecuted by a computer processor is disclosed, the computer programinstructions defining the steps of: receiving a first event from aclient, the first event comprising a streaming event; determining thatthe first event comprises a primary event; writing the first event to acache and returning the first event to the client; receiving a secondevent from the client, the second event associated with the first event;annotating the second event based on the first event; and returning theannotated second event to the client.

The illustrated embodiments provide numerous benefits over existingpipelines. The disclosed embodiments reduce data processing andcertification times by certifying events using a stream processor versusa batch processor. Thus, the illustrated embodiments, do not require a“waiting” period prior to certifying results and can certify results inreal-time or near real-time. The disclosed embodiments additionallyutilize a single pipeline and thus do not require the hardwareduplication, software complexity, and human resources required by Lambdapipelines. Relatedly, since application-level code must only be deployedonce, rapid changes in data processing can be implemented withoutrequiring separate development workflows. Additionally, since only onecodebase is used, there is no risk of variations in processing betweenpipelines. Finally, in existing pipelines, sacrifices for speed can leadto a more significant variation between the initially posted resultsfrom the streaming pipeline and the final results from batch processing.As the latency of batch increases relative to streaming, this can leadto a lack of confidence in reporting as the variation becomes morepronounced. The disclosed embodiments alleviate this deficiency.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a block diagram illustrating a processing system employing aLambda architecture.

FIG. 1B is a block diagram illustrating a processing system employing aKappa architecture.

FIG. 2 is a block diagram illustrating a data processing systemaccording to some embodiments of the disclosure.

FIG. 3 is a block diagram illustrating a pipeline factory according tosome embodiments of the disclosure.

FIG. 4 is a block diagram illustrating a core pipeline according to someembodiments of the disclosure.

FIG. 5 is a block diagram illustrating a pluggable join framework forstream processors according to some embodiments of the disclosure.

FIG. 6A is a flow diagram illustrating a method for performing anin-order join using a pluggable join framework according to someembodiments of the disclosure.

FIGS. 6B and 6C are flow diagrams illustrating a method for performingan out-of-order join using a pluggable join framework according to someembodiments of the disclosure.

FIG. 7 is a schematic diagram illustrating a computing device showing anexample embodiment of a client or server device used in the variousembodiments of the disclosure.

DETAILED DESCRIPTION

FIG. 1A is a block diagram illustrating a processing system employing aLambda architecture.

In the illustrated embodiment, events in the system (100 a) originatefrom one or more event emitters (102). As used herein, an event refersto any type of data generated by a computing system. Generally, mostevents include arbitrary data as well as a timestamp indicating when theevent emitter (102) generated the data. Alternatively, or in conjunctionwith the preceding, the system (100 a) adds a timestamp representing thetime the pipelines (106, 108) receive the event. In some embodiments,the timestamp comprises a standard time (e.g., based on a 24-hourclock). In some embodiments, the timestamp comprises a numerical value(e.g., time since UNIX epoch). In other embodiments, the timestamp maycomprise a sequence number or other incrementing (or otherwise changing)value. In some embodiments, events further include nonce values toensure uniqueness.

The event emitters (102) can comprise any computing system capable ofgenerating data. The disclosure places no limitations on the type ofdata or type of systems capable of generating such data. As one example,an event emitter may include a digital analytics system configured totrack and monitor user events on webpages or in mobile apps. A digitalanalytics platform generates many events as users access products. Oneexample is the delivery of advertising creatives. In these scenarios,the analytics platform generates an event indicating that a servertransmitted the creative to the end-user. The analytics platform alsogenerates an event indicating that the end-user device displayed thecreative (i.e., an impression). If the end-user interacts with thecreative, the analytics platform generates a “click” event (which may beany type of interaction including touch events and thus is not limitedto physical mouse clicks). In certain embodiments, the analyticsplatform also generates conversion events that indicate that after animpression, and after a click, the end-user has completed another action(e.g., completes a digital purchase) that is related to the previousevents. In some embodiments, the analytics platform tracks all of theseevents via a client-side identifier stored in, for example, a cookie orother end-user storage mechanism.

In some embodiments, event emitters (102) are part of the system (100a). That is, in some embodiments, the system (100 a) includes and hassome level of control over the event emitters (102). Examples of thistype of arrangement include internal data sources for an organization(e.g., internal analytics tracking). In other embodiments, the eventemitters (102) comprise third-party systems. In some embodiments, thesystem (100 a) receives events from both internal and external eventemitters (102).

In either scenario, event emitters (102) transmit events over atransport layer (104). The transport layer (104) comprises one or morenetwork protocols and one or more physical media used for transportingdata. The disclosure does not unduly limit the structure of thetransport layer. In some embodiments, the system (100 a) uses anInternet protocol suite (e.g., transmission control protocol (TCP) andInternet protocol (IP)) as the transport layer (104). The system (100 a)may use other models such as those adhering to the Open SystemsInterconnection (OSI) model or other types of protocol models. In someembodiments, the transport layer (104) performs other operations on theevents beyond network routing (e.g., TCP/IP). For example, the transportlayer (104) may compress events using, as an example, gzip or othercompression algorithms.

The specific internal workings of the transport layer (104) are notlimiting, and the system (100 a) may ignore various features of thetransport layer (104) that are handled entirely in the transport layer(e.g., congestion control in a TCP layer). However, as discussed in moredetail herein, the transport layer (104) may include inherent datatransfer characteristics that impact the processing of the data bysystems. One example, discussed in more detail in FIG. 2 et seq, is thatsome transport layer (104) designs may unintentionally (or, in somecases, intentionally) duplicate events transmitted over a network. Insuch networks, the event emitters (102) transmit one event, but thepipelines (106, 108) receive two or more events. A more concrete exampleof such a transport layer is a publish-subscribe system such as Apache®Kafka, which can provide “at least once” delivery of events.

As illustrated, the system (100 a) routes events from the transportlayer (104) to both a streaming pipeline (106) and a batch pipeline(108). In the illustrated embodiment, the batch pipeline (108) processesdata in batches. As used herein, a batch refers to a period in which thebatch pipeline (108) analyzes data (e.g., every hour). The disclosuredoes not describe the specific inner workings of the batch pipeline(108) in detail; however, the batch pipeline (108) comprises anyprocessing system that provides accurate processing of data. Examples ofbatch pipelines include Hadoop clusters. The batch pipeline (108)ensures this accuracy by running slowly and at fixed intervals uponreceiving all needed data. Since the batch pipeline (108) requires afixed period of data (e.g., one hour) and a second fixed period toprocess the data (e.g., three hours), the batch pipelines (108) areconsistently “behind” the current time. That is, when the batch pipeline(108) writes data to the data warehouse (110), the data written is“stale” by a fixed amount of time (e.g., four hours in the previousexamples). However, as stated above, consumers of the batch-processeddata can be confident that the data is accurate.

As a brief aside, before Lambda systems, big data systems often onlyincluded a batch pipeline (108) and did not include a streaming pipeline(106). As a result, such systems produced consistently delayed results.To remedy this delay, the system (100 a) includes a streaming pipeline(106). Such a pipeline may comprise one or more stream processors suchas Apache® Storm processors or similar stream processors. In contrast tothe batch pipeline, the streaming pipeline (106) processes data inreal-time or near real-time. Thus, when the streaming pipeline (106)receives an event over the transport layer (104), it immediatelyprocesses or transforms the event and writes the processed event to thedata warehouse (110).

Since the streaming pipeline (106) processes events quickly and inisolation, the streaming pipeline (106) may introduce errors in theprocessed data. For example, the streaming pipeline (106) generally doesnot guard against writing duplicate data if the pipeline (106) receivesduplicate events. Similarly, the streaming pipeline (106) mayinadvertently drop some events. Thus, the streaming pipeline (106) isfast but inaccurate.

In the illustrated embodiment, the data warehouse (110) segments datareceived from the streaming pipeline (106) and the batch pipeline (108)into two separate storage areas. Additionally, as the batch pipeline(108) “catches up” to the data processed by the streaming pipeline(106), the data warehouse (110) overwrites the results of the streamingpipeline (108). Thus, at any given moment, the data warehouse (110)stores accurate, batch-processed data and a smaller, more recent subsetof inaccurate stream-processed data. Absent system failures, the sizesubset of the inaccurate data remains constant while the size of theaccurate data increases over time.

To support the above format of the data warehouse, the system (100 a)must duplicate logic between the streaming pipeline (106) and the batchpipeline (108). Since the streaming results must be “reconciled” withthe results of the batch processing, the streaming pipeline (106) andbatch pipeline (108) must process the events in the same manner. Thisrequirement doubles both the development time and the computingresources needed to support both pipelines (106, 108). Additionally, thesystem (100 a) requires additional software and hardware to enable thedata warehouse (110) to perform the reconciliation process after thecompletion of each batch processing job.

FIG. 1B is a block diagram illustrating a processing system employing aKappa architecture. The illustrated system (100 b) solves some of theproblems of Lambda architectures, as discussed in the preceding figure.However, the system (100 b introduces additional problems and fails toprovide full batch support.

Various elements of the system (100 b) are identical, or nearlyidentical, to those similarly numbered elements of FIG. 1A. The eventemitters (102) and the data transport layer (104) perform the samefunctions as previously described. Also, the streaming pipeline (106)may perform many, if not all, of the same operations of the streamingpipeline (106) discussed in FIG. 1A.

As illustrated, the streaming pipeline (106) receives events generatedby the event emitters (102) over the data transport layer (104). Thestreaming pipeline (106) processes this data and writes the processeddata to the data warehouse (116). In contrast to the data warehouse(110) in FIG. 1A, the data warehouse (116) may only include a singlestorage area for data given the absence of a batch processing layer.

As described in the description of the previous system (100 a),streaming pipelines (106) generally cannot guarantee the accuracy ofdata processing. Some systems (e.g., 100 b) remedy this problem byemploying “micro batching” whereby small batches of stream events areprocessed simultaneously. In general, these batches representmilliseconds of events, thus providing reasonable speed while simulatingsmall batches. Micro-batching, however, fails to provide the level ofaccuracy provided by larger (e.g., one hour) batches. Another techniqueuses recompute logic (114) to re-process streaming events when the logicof the streaming pipeline (106) changes or based on other requirements.In this scenario, the system (100 b) can store raw events in the rawevents storage module (112), the recompute logic (114) retrieves theseevents. The recompute logic (114) then streams the events into thestream pipeline (106) for re-processing. In one scenario, the recomputelogic (114) executes when the system (100 b) changes the processinglogic of the streaming pipeline. Thus, if the system (100 b) modifieshow the streaming pipeline (106) processes events, the recompute logic(114) simulates a historical event stream. In another embodiment, therecompute logic (114) can stream data from the raw events storage module(112) to the streaming pipeline (106) at fixed intervals, thussimulating a batch processing mode. However, there are numerouschallenges to this approach that limit its effectiveness. First, datafrom the raw events storage module (112) must be re-streamed in the sameorder as streamed initially, to ensure the integrity of there-processing. Thus, the recompute logic (114) reproduces inaccuraciesrelating to out-of-order events during the re-streaming. Second, theinfrastructure that supports the streaming pipeline (106) generallycannot handle significant increases in streaming data, thus limiting thetotal amount of re-streamed data the streaming pipeline (106) can handleat any given time. Third, and most importantly, the streaming pipeline(106) cannot inherently perform various operations that a batch pipeline(108) can perform, such as joins or aggregations. Thus, even ifre-streamed, the output of the streaming pipeline (106) always lacksthese advanced operations.

FIG. 2 is a block diagram illustrating a data processing systemaccording to some embodiments of the disclosure.

The illustrated system (200) segments the data processing into multiplelogical layers. In some embodiments, these layers may also comprisephysical layers, with each layer physically connected via a networkinterconnect. The illustrated layers comprise serving (220 a), datatransport (220 b), pipeline factory (220 c), packaging (220 d), andwarehousing (220 e) layers.

The serving layer (220 a) includes one or more event emitters (202). Inthe illustrated embodiment, these event emitters (202) can be similar oridentical to the event emitters (102) discussed previously. As a fewexamples, the event emitters (202) can comprise systems including, butnot limited to, ad servers, web servers, and beacon servers, thatproduce raw traffic events and send the events factory layer (220 c) viathe data transport layer (220 b). In the illustrated embodiment, thedata transport layer (220 b) represents the previously described datatransport (204). In the illustrated embodiment, the data transport layer(220 b) comprises multiple network topologies and protocols that, whencombined, deliver events to the factory layer (220 c).

In the illustrated embodiment, the factory layer (220 c) receives rawevents from the data transport layer (220 b) and processes the eventsvia a core pipeline (210). The description of FIG. 3 provides furtherdetail regarding the factory layer (220 c), and the description of FIG.4 provides further detail regarding the core pipeline (210). Thus, thefollowing description of the factory layer (220 c) only brieflydescribes the layer (220 c) and the core pipeline (210), and FIGS. 3 and4 present further detail.

The factory layer (220 c) is responsible for doing the bulk of theprocessing of event traffic via the core pipeline (210). The followingdescription describes exemplary processing operations performed by thecore pipeline (210). The core pipeline (210) may perform some or all ofthe following operations as well as additional operations.

In one embodiment, in the serving (220 a) and data transport (220 b)layers, devices often compress and bundle data to conserve bandwidth. Asa result, the core pipeline (210) may perform a parsing operation thatunpacks or processes complex data structures (e.g., blobs) so thatdownstream consumer systems can access the data. Thus, as one example,the core pipeline (210) can detect that an incoming event was compressedusing a gzip algorithm and may first unzip the event.

In another embodiment, the core pipeline (210) performs explosionoperations. An explosion operation comprises unpacking composite events.For example, a multi-serve event comprises an event indicating that anend-user device received a set of content to be displayed. Thus, themulti-serve event comprises a data structure describing multiple itemsof content (e.g., advertisements). The core pipeline (210) may transforma single multi-serve event into multiple single-serve events such thateach item of content in the event is associated with an independentevent for later processing.

In another embodiment, the core pipeline (210) performs metadataannotation operations. As illustrated, the core pipeline (210)communicates with a metadata store (208). In one embodiment, themetadata store (208) comprises a data storage device such as a MySQLdatabase or other type of relational database. In other embodiments, themetadata store (208) may comprise other types of data storage devices(e.g., a key-value data store). The core pipeline (210) accesses themetadata store (208) to perform dimensional annotation on incoming eventdata. As used herein, dimensional annotation refers to the augmenting ofdata with additional other data. For example, a content serving eventmay only a line item identifier identifying the served content. The corepipeline (210) may access the metadata store (208) and look up a parentinsertion order, an advertiser identifier, and an organization for thatline item identifier. The core pipeline (210) may then augment the lineitem identifier with this metadata to generate an annotated event. Inthis way, downstream consumer systems can group and aggregate based onthe line item identifier.

In another embodiment, the core pipeline (210) performs trafficannotations. A traffic annotation comprises a complex join of an eventwith a prior event. For example, a click event may need to be joinedwith a first impression event to annotate the click with auctioninformation or targeting information that is only available in the firstimpression.

In another embodiment, the core pipeline (210) performs arbitrarycomputations dictated by business logic. An example of this type ofcomputation is a currency conversion. By doing the operation only oncein the core pipeline (210), the system (200) can ensure consistencyacross all subsequent consumer systems, rather than requiring downstreamconsumer systems to implement the same rules and possibly arrive atdifferent results.

In another embodiment, the core pipeline (210) validates incomingevents. In this embodiment, the core pipeline (210) can filter eventsbased on traffic conditions.

In another embodiment, the core pipeline (210) performs deduplication onincoming events. As discussed previously, the data transport layer (220b) may support “at least once” semantics. Alternatively, or inconjunction with the preceding, event emitters may allow duplicateevents. Regardless of the source of duplication, the core pipeline (210)ensures that all events are processed and stored once and notduplicated. For example, the core pipeline (210) may allow more than oneclick event per impression event during a given period.

In another embodiment, the core pipeline (210) performs normalization onthe received events. During a normalization operation, the core pipeline(210) “fits” an event to a particular schema or layout to facilitatereporting. This schema or layout is typically a standard field alignmentand transformation.

Finally, in some embodiments, the core pipeline (210) performs a fastfeedback operation. In this operation, the core pipeline (210) providesfeeds or streams of data at very low latency to low-latency consumers(206) such as an ad serving budget control system. Typically, mostconsumer systems wait until the core pipeline (210) has completed allprocessing steps; however, some consumer systems are willing tosacrifice quality for timing. These specialty stages can be critical tosome consumer systems.

In general, the core pipeline (210) processes events linearly: thequality of the event data increases as data passes from one processingoperation to the next. Ultimately, after the core pipeline (210) appliesall operations to the event data, the core pipeline (210) writes theprocessed event to one or more fact feeds (212). In the illustratedembodiment, a fact feed (212) comprises a log of every event that wasreceived by the core pipeline (210) and any additional information thatthe core pipeline (210) annotates or computes. The fact feeds (210)become the source of truth for the entire system (200). By having thecore pipeline (210) compute the fact feed (212) used by subsequentconsumers pipelines (214 a, 214 b, 214 n), the overall quality of thesystem (200) is improved.

Since the system uses a centralized fact feed (212), the core pipeline(210) never removes any field from an event. Additionally, the corepipeline (210) does not modify any raw field that it receives from thecore pipeline (210) from the data highway (204). However, as oneexception, the core pipeline (210) may replace null or empty fields witha static or default value, as this may assist downstream consumersystems (214 a, 214 b, 214 n). In most embodiments, the core pipeline(210) does not attempt to “correct” or “fix” invalid values in an event.However, the core pipeline (210) may deviate from this requirement torecover from failed launches or bugs. In some embodiments, if the corepipeline (210) violates this requirement and fixes an invalid value inan event, the core pipeline (210) annotates the record with a flag sothat a downstream consumer system can monitor the rule.

Importantly, the core pipeline (210) also ensures that no event isduplicated in the final fact feed (212). Thus, the core pipeline (210)never intentionally duplicates or allows duplicate events to result fromthe operations.

In the illustrated embodiment, the packaging layer (220 d) comprisesvarious consumer pipelines (214 a, 214 b, . . . 214 n) retrieve orreceive data from the fact feed (212). The packaging layer (220 d)accesses the fact feed (212) and provides the processed events thereinto downstream consumer pipelines (214 a, 214 b, . . . 214 n). Whereasthe factory layer (220 c) is typically a complex, but linear processingstage, the packaging layer (220 d) is typically composed of multipleparallel consumer pipelines (214 a, 214 b, . . . 214 n). Consumerpipelines (214 a, 214 b, . . . 214 n) are typically minimal, possiblysingle-stage pipelines that project and aggregate the events in the factfeed (212) for loading into a warehouse (e.g., 218 a, 218 b, . . . 218n) or similar system. The availability of the fact feed (212) triggersconsumer pipelines (214 a, 214 b, . . . 214 n), and thus the consumerpipelines (214 a, 214 b, . . . 214 n) may run in parallel with oneanother.

In some instances, the consumer pipelines (214 a, 214 b, . . . 214 n)are external to the factory layer (220 c) and warehouse layer (220 e).In other instances, the system (200) includes and controls the consumerpipelines (214 a, 214 b, . . . 214 n). Alternatively, or in conjunctionwith the preceding, the warehousing layer (220 e) may be external to thesystem (200). In various embodiments, the consumer pipelines (214 a, 214b, . . . 214 n) generally perform some or all of the followingoperations (or combinations thereof).

In one embodiment, the consumer pipelines (214 a, 214 b, . . . 214 n)perform mapping and transformation operations. In these operations, theconsumer pipelines (214 a, 214 b, . . . 214 n) may require the data in aformat different than the format of the fact feed (212). For example,the consumer pipelines (214 a, 214 b, . . . 214 n) may map enumeratedvalues (possibly in a lossy fashion) to fit a further downstreamconsumer data model.

In another embodiment, the consumer pipelines (214 a, 214 b, . . . 214n) perform projection operations. In some embodiments, consumerpipelines (214 a, 214 b, . . . 214 n) will typically not require everyfield of the fact feed (212). Thus, the consumer pipelines (214 a, 214b, . . . 214 n) only ingest a small fraction of the available columns.

In another embodiment, the consumer pipelines (214 a, 214 b, . . . 214n) perform aggregation operations. In some embodiments, the consumerpipelines (214 a, 214 b, . . . 214 n) aggregate facts and produce metricfields for efficient loading into a database or similar data store.

In another embodiment, the consumer pipelines (214 a, 214 b, . . . 214n) perform reverse annotation joins (e.g., right outer joins). In someembodiments, the consumer pipelines (214 a, 214 b, . . . 214 n) performjoin operations that cannot be implemented efficiently within the corepipeline (210). For example, a data science consumer pipeline mayrequire a feed containing every impression event joined to any futureclick events recorded in the fact feed (212). Because this type ofpipeline requires data collected over a long period before processingcan begin, it would negatively impact all consumer pipelines (214 a, 214b, . . . 214 n) to wait. Therefore, the pipeline performs these joins inbatch outside of the core pipeline (210).

In another embodiment, the consumer pipelines (214 a, 214 b, . . . 214n) perform rollup operations. In some embodiments, the consumerpipelines (214 a, 214 b, . . . 214 n) may choose to create rollup feedsof the raw facts stored in fact feed (212). For example, the consumerpipelines (214 a, 214 b, . . . 214 n) may create an hourly feed from afive-minute fact feed. The consumer pipelines (214 a, 214 b, . . . 214n) may perform this operation to use fewer filenames in a distributefiled system (e.g., the Hadoop Filesystem, HDFS) since such a filesystem collapses multiple files into larger single files. Further, therollup may typically transform the data into a columnar format likeOptimized Row Columnar (ORC) to promote faster ad hoc projection.

In another embodiment, the consumer pipelines (214 a, 214 b, . . . 214n) perform sketch operations. In some embodiments, as the consumerpipelines (214 a, 214 b, . . . 214 n) generate aggregates, the consumerpipelines (214 a, 214 b, . . . 214 n) may produce aggregate sketchcolumns to capture unique users or similar complex computations. Theconsumer pipelines (214 a, 214 b, 214 n) can perform this expensiveoperation once on behalf of multiple end-users or downstream systems.

In another embodiment, the consumer pipelines (214 a, 214 b, . . . 214n) perform cleansing operations. In some embodiments, the consumerpipelines (214 a, 214 b, . . . 214 n) may cleanse data in the fact feed(212) for a specific purpose. For example, cookies or personallyidentifiable information (PII) might need to be anonymized, or theconsumer pipelines (214 a, 214 b, . . . 214 n) may need to obscure datato enforce data visibility controls.

In some embodiments, the consumer pipelines (214 a, 214 b, . . . 214 n)can be hierarchal. That is, a first consumer pipeline may perform one ormore shared steps, and downstream consumer pipelines use the output ofthe first consumer pipeline as input.

After processing by consumer pipelines (214 a, 214 b, . . . 214 n), eachof the consumer pipelines (214 a, 214 b, . . . 214 n) output furtherprocessed event data to respective data warehouses (218 a, 218 b, . . .218 n) in the warehousing layer (220 e). The warehousing layer (220 e)is generally the final stage of the system (200), where data is loadedinto various systems to facilitate reporting, billing, or analysis. Adata team may be responsible for various aspects of the warehousing, orit may be delegated to a data customer instead. Operations for a datateam include loading, replication, and verification. In loadingoperations, the system (200) may need to load the data into a datawarehouse (e.g., an Oracle or Druid data warehouse) or place the dataonto a shared drop box or similar system. In replication operations, thesystem (200) may need to replicate a data feed to another dataprocessing (e.g., Hadoop) cluster in a different co-location. In averification operation, the system (200) may need to verify that thedata loaded into a warehouse (218 a, 218 b, . . . 218 n) accuratelymatches the original fact feed (210) (i.e. certify there was no dataloss).

As illustrated, in some embodiments, data bypasses the packaging layer(220 d). In these embodiments, the core pipeline (210) streams outputdirectly to a real-time data warehouse (216). In the illustratedembodiment, the real-time data warehouse (216). In the illustratedembodiment, the system (200) may use a real-time data warehouse (216)for reporting or similar functions that do not require high dataaccuracy.

FIG. 3 is a block diagram illustrating a pipeline factory according tosome embodiments of the disclosure.

In the illustrated embodiment, a data highway (204) delivers events fromone or more event emitters (not illustrated) to a factory layer (220 c)and raw event storage (302). The description of FIG. 2 provides furtherdetail regarding the data highway (204) which is not repeated herein.

In the illustrated embodiment, the raw event storage (302) may comprisea distributed file system (e.g., HDFS). In one embodiment, the system(300) writes raw events to the raw event storage (302) as they arereceived. In some embodiments, the system (300) writes the raw events toraw event storage (302) in a batch mode. That is, the system (300)writes a separate file for each batch period (e.g., one hour), the fileincluding all events received during that period. In some embodiments,not illustrated, external consumer systems can access the raw eventstorage (302) to perform batch processing. Thus, in some embodiments,the raw event storage (302) can be used to provide backwardscompatibility with existing batch pipelines.

As illustrated, a stream processor (304) receives events from the datahighway (204). In one embodiment, the stream processor (304) comprises adistributed stream processor. In one embodiment, the stream processor(304) comprises a streaming topology that defines data processing stagesto perform on events.

One example of a stream processor (304) is an Apache® Storm topology.Briefly, a Storm topology is a graph of inputs and processing nodes. Thetopology receives events as input streams. Each event in the inputstream comprises a tuple and the input stream itself is an unboundedseries of such tuples. The topology receives streams from input sources,referred to as “spouts.” The topology performs all processing inindividual processing nodes, referred to as “bolts.” The topologydefines the input to a bolt as either a spout or another bolt. Thus, thetopology defines connects between spouts and bolts. The output of one ormore bolts forms the output of the topology.

In the illustrated embodiment, the stream processor (304) performs anyor all of the processing operations described in the description of corepipeline (210) in FIG. 2. Details of these operations are not repeatedherein. Importantly, the stream processor (304) ensures that a givenevent received over the data highway (204) is output at most once to thestreaming queue(s) (306). Thus, during processing, the stream processor(304) detects and drops any duplicated events. FIG. 4 provides furtherdetail regarding specific techniques for performing this detection anddropping.

As illustrated, the stream processor (304) outputs the processed andde-duplicated event stream to one or more streaming queues (306). In oneembodiment, the streaming queues (306) comprise one or more Apache®Kafka queues. Since the event stream is processed by the streamprocessor (304), the data stored in the streaming queues (306) can beconsidered as source of truth for downstream consumers. Thus, alow-latency consumer system (206) can directly access the streamingqueues (306). In this manner, the system (300) can simulate a fullystreaming pipeline. As will be discussed, since the stream processor(304) processes the event stream and ensures that no records are droppedor duplicated, the simulated stream in the streaming queues (306) ismore accurate than a raw event stream. Furthermore, as will bediscussed, the output of the stream processor (304) includes the resultsof more complicated or advance operations (e.g., joins or dimensionalannotation) which are not possible using traditional stream processingtechniques.

A spooler (308) and auditor (310) use the output of the stream processor(304) to support advanced operations by the stream processor (304). FIG.4 provides more detail regarding the spooler (308) and reference is madeto that description.

In one embodiment, the spooler (308) comprises a second streamprocessor. The spooler (308) ensures that a one-to-one mapping betweenstreamed data and data written to the fact feed (210) exists. Thespooler (308) also ensures that streaming events retrieved from thequeues (306) appears exactly once in the fact feed (210) (i.e., noevents in the queues, 306, are duplicated). As such, the spooler (308)may comprise a separate stream topology similar to the stream processor(304). In contrast to the stream processor (304), the spooler (308)reads events from the streaming queues (306). Thus, the event stream tothe spooler (308) comprises the processed events. As illustrated, priorto writing to the fact feed (210), the spooler (308) outputs to theauditor (310) via a buffer (312). In one embodiment, the output of thespooler (308) comprises a flat file (e.g., an HDFS file) and the buffer(312) comprises a distributed file system such as HDFS. In oneembodiment, this flat file comprises a set of events occurring in agiven batch period. Thus, the flat file simulates batch processing, butusing the streaming events.

In the illustrated embodiment, an auditor (310) receives the output ofthe spooler (308). As described above, in some embodiments, the outputof the spooler (308) comprises a batch file of events. In theillustrated embodiment, the auditor (310) also accesses raw eventstorage (302). In one embodiment, the format of the raw event storage(302) and the output of the spooler (308) are the same. For example,spooler (308) may write flat files to HDFS buffer (312) and raw eventstorage (302) may comprise raw events stored in the same type of file(e.g., HDFS). In the illustrated embodiment, the auditor (310) retrievesa batch file from buffer (312). In one embodiment, this batch file isassociated with a fixed period. In some embodiments, this fixed periodis represented in the filename or in metadata. Using this fixed period,the auditor (310) then retrieves a set of events from the raw eventstorage (302) matching the fixed period. In one embodiment, the periodsof the buffer (312) and the raw event storage (302) are synchronized. Inthis embodiment, the auditor (310) then retrieves a single file from theraw event storage (302) that matches the period pulled from the buffer(312). In other embodiments, the auditor (310) may execute a MapReducejob to identify events split across multiple files. In this embodiment,the periods represented by files in the raw event storage are notsynchronized with the buffer (312). Thus, the auditor (310) must patchtogether portions of multiple files stored in raw events storage (302)to rebuild a period of raw events matching the period stored in thebuffer (312). In either event, the auditor (310) receives two filescontaining raw events from raw event storage (302) and a set ofprocessed events for the same period stored in buffer (312).

In general, the auditor (310) ensures that each processed event in thebuffer (312) matches a raw event stored in raw event storage (302).Thus, the auditor (310) ensures that no events were dropped duringprocessing by the stream processor (304) and that no events wereduplicated. If the auditor (310) detects that an event exists in the rawevent storage (302) and does not exist in the corresponding buffer (312)output, the auditor (310) sends the missing event back to the streamprocessor (304) for re-processing.

The stream processor (304) reprocesses the events using the sameprocessing logic used to process the event originally. In someembodiments, the stream processor (304) may add a field to thereprocessed event to indicate it was (or will be) reprocessed. In mostembodiments, the stream processor (304) will properly process the eventduring re-processing. However, if the stream processor (304) cannotreprocess the event (as detected by the auditor, 310), the system (300)may gracefully handle the error. In one embodiment, the auditor (310)can itself add a field to the raw event indicating that the raw eventwas not processed and write the event along with the processed events.

After any missing events are re-processed, the auditor (310) writes thefinal output to the fact feed (210). Since spooler (308), buffer (312)and auditor (310) operate on batches of events, the fact feed (210)comprises a simulated batch data store. In some embodiments, the auditor(310) will delay writing to the fact feed (210) until any events arere-processed. In other embodiments, the auditor (310) writes thepartially final output file to the fact feed (210) and updates the fileupon completing the re-processing.

FIG. 4 is a block diagram illustrating a core pipeline according to someembodiments of the disclosure. Various elements of FIG. 4 are describedin the previous figures and those elements are not described againherein.

In the illustrated embodiment, a stream processor (304) receives eventsfrom a data highway (204). In the illustrated embodiment, the streamprocessor (304) receives events from the data highway (204) via aninitial spout (404). The stream processor (304) as illustrated includestwo separate spouts (404, 422). In the illustrated embodiment, thestream processor (304) utilizes two spouts (404, 422) to distinguishbetween event streams (e.g., original versus re-processing). In theillustrated embodiment, the stream processor (304) topology can beconfigured to add additional extract-transform-load (ETL) steps (e.g.,bolts) for the reprocessing spout (422) versus events received via theinitial spout (404).

In the illustrated embodiment, the stream processor (304) processesevents received via spouts (404, 422) via ETL logic (406). As describedpreviously, ETL logic (406) may comprise a series of linear processingstages (e.g., bolts) for each operation performed on events.

In the illustrated embodiment, the ETL logic (406) outputs processedevents to two streaming queues (408 a, 408 b). In one embodiment, thetwo queues (408 a, 408 b) store varying types of event data. Asillustrated, a first queue (408 a) is accessed by a partial streamconsumer system (424). In the illustrated embodiment, the first queue(408 a) may be filled by the ETL logic (406) prior to the execution ofall processing steps. In the illustrated embodiment, the ETL logic (406)may eschew more complicated and time-consuming operations and interruptthe full processing steps to provide low latency operations. In someembodiments, this bypassing includes foregoing joins, trafficprotection, annotation, etc. In the illustrated embodiment, the partialstream consumer system (424) may comprise a fast feedback system such asbudget or pacing systems that are willing to accept a certain level oferror. Thus, the first queue (408 a) provides “best effort” data whereinthe system (400) does not guarantee the accuracy of the data. Inpractice, however, the system (400) will generally process a largeamount of data correctly enough that the best effort data in the firstqueue (408 a) is of value to the partial stream consumer system (424).

In contrast to the first queue (408 a), the stream processor (302) fillsthe second queue (408 b) with the results of the full ETL processing.Thus, the ETL logic (406) fully processes the data in the second queue(408 b), including performing joins, deduplication, annotations, frauddetection, traffic protection, etc. In one embodiment, the completestreaming consumer system (426) access second queue (408 b) can retrievedata that achieves close to exactly once performance (that is, no eventsare dropped or duplicated) since the data was fully processed in the ETLlogic (406). In some embodiments, this performance will meet “exactlyonce” performance. However, in other embodiments, the output of thesecond queue (408 b) is still subject to inaccuracies caused by theunderlying messaging queue. In some embodiments, a near exactly onecompleteness from second queue (408 b) comprises a 99.9% guarantee ofcompleteness. Such a confidence level is often suitable for applicationssuch as real-time reporting.

Finally, as illustrated and discussed above, a final fact feed (210)meets exactly once requirements of all systems and provide batch-likeperformance. That is, data in the fact feed (210) will be fullyde-duplicated and ensure that no events were dropped. As discussed inFIG. 3, this guarantee is implemented via spooler (308) and auditor(310). Auditor (310) is described more fully in FIG. 3 and those detailsare incorporated herein by reference.

In the illustrated embodiment, the spooler (308) is illustrated asincluding deduplication writer (412), deduplication store (414), and afact feed writer (416).

In the illustrated embodiment, the deduplication writer (412) receivesevents from the second queue (408 b). An event is uniquely identified byan event identifier (event_id). The spooler (308) considers two eventsas duplicates if they have the same event identifier. Events may includeadditional, but standardized, fields such as a type, timestamp, joinstatus, and secondary event identifiers.

The deduplication writer (412) writes each of the events todeduplication store (414). In one embodiment, the store (414) comprisesa database such as HBase or a similar storage device. Upon receiving anevent, the writer (412) analyzes the fields associated with the event.If the event includes one or more secondary event identifiers, thewriter (412) will retrieve all events stored in store (414) matchingthese secondary event identifiers and update the entries to indicatethat a primary event is available (i.e., will be written to the store,414). The writer (412) will then write the received event to the store(414) using the event identifier as a key. In some embodiments, a saltwill be added to the event identifier before using the event identifieras a key. In the illustrated embodiment, the writer (412) will not writethe event if the event has secondary event identifiers and the initialstep of updating the secondary events is not successful. In someembodiments, the writer (412) will serialize the event prior to writingthe event as a value for the event identifier key.

In the illustrated embodiment, the deduplication store (414) storesevents per batch period and per type of event. In some embodiments, thestore (414) creates a new table for each event type and batch periodpair for a fixed period of time (e.g., one week) since the current time.The store (414) additionally includes a pruning process thatperiodically inspects the created tables and removes older tables notoccurring within the current period (e.g., older than one week). In someembodiments, the auditor (310) initiates this pruning process uponconfirming that all data for a given period is certified.

The spooler (308) additionally includes a fact feed writer (416). In theillustrated embodiment, the fact feed writer (416) waits for a signalfrom auditor (310) to trigger a spooling process to write the events inthe store (414) to the fact feed (210) for a particular batch period andevent type. In one embodiment, the fact feed writer (416) includes aninternal web server that comprises a Hypertext Transfer Protocol (HTTP)endpoint that is called by the auditor (310) to initiate the spooling.As described above, once the auditor (310) confirms that the data in thestore (414) is fully processed and certified, the auditor (310) issues acall to the endpoint which causes the writer (416) to start writing tothe fact feed (210). In one embodiment, the writer (416) executes adistributed process routine to per from a full table scan of the store(414) and write the events to the fact feed (210).

For each event in the store (414), the writer (416) will deduplicate theevents prior to writing. In one embodiment, the writer (416) will firstdetermine if an event has one or more secondary identifiers and whetherthat secondary event was successfully joined to the event underinspection. If so, the writer (416) will select the most recentsecondary event and write that joined event to the fact feed (210).Alternatively, if the event under inspection indicates that a primaryevent is available, the writer (416) will skip the event (since a rootevent exists). Finally, if the event does not have secondary identifiersand the primary event flag is not raised, the writer (416) will writeout the event as failed since the secondary event was not properlyjoined.

In some embodiments, low-latency consumers may not want to or be able toconsume a low-latency stream (408 a) directly. For example, the streammight contain personally-identifiable fields that need to be restrictedto specific consumers or the final consumer may need additionalprocessing of events for their use. As another example, the consumer maybe consuming from many sources and is unable to handle different eventschemas of their various inputs. In these scenarios, the system (400)provides derived low-latency streams, or “filters”, that have all of theevents (or at least all of the desired events) as the second queue (408b) stream. Each filter can be associated with a quality of service (QoS)level. In the illustrated embodiment, three QoS levels are provided: “atleast once”, “at most once”, and “at least once with tag.”

A filter having an at least once QoS outputs every event but potentiallyincludes duplicates. In the event of a system (400) failure, the atleast once filter resends previously-sent events. A filter having an atmost once QoS does not include duplicates but potentially drops data.The at most once filter does not reprocess the same event batch morethan once.

Finally, a filter having an at least once with tag QoS generates batchdataset wherein each event in the batch includes tags allowingdownstream consumer systems to detect duplicates. In one embodiment,this filter includes a stream topic, partition, and a “cursor,” that canbe used to detect duplicates. In some embodiments, Kafka offsets and CMSMessage Ids could provide such cursors. The consumer system is thenresponsible for keeping track of the last cursor it processed, anddiscard any subsequent batch with a cursor less than or equal the newbatch. This requires a 1-to-1 correspondence between batches in thepipeline and derived streams.

Each of the above filters may be implemented via a separate streamprocessor (e.g., stream topology). In these embodiments, the filtersutilize an output of the system (400) (e.g., queues 408 a, 408 b) as aninput source (e.g., spout) and output the filtered feed.

For the at least one filter, the filter will always back up in the eventof a failure and resend any events that cannot be confirmed as beingsuccessfully delivered. This filter uses the initial spout (404) andstreaming queue (408 b) as inputs (e.g., filter spouts). In thisembodiment, the consumer is configured to not report its current readoffset. When sending data, the filter spout includes the current eventscursor in a message identifier. The receiver (e.g., sink) would thenacknowledge the received message only after successfully delivering thefiltered output to the derived stream. In some embodiments, the receivercould also use the existing spooler logic to fail a tuple if it can'tdeliver it, and then continue to fail subsequent tuples until itreceives a restarting indication from the spout. Upon receipt of anacknowledgement, the filter spout would commit that cursor back to thesystem (400). On receipt of a fail of a sent event, the filter spoutwould back up the received offset to a cursor at or before the lastacknowledged event and restart sending.

For the at most once filter, the filter spout enables automaticallycommitting offsets in a stream queue. By turning on auto-commitment, thefilter spout only transmits a given event once and does not re-transmitevents causing duplication.

For the at least once with tag filter, the at least one filter mechanismcan be used. However, in this filter, tags will be added prior totransmission to the consumer. These tags include the cursor, asdescribed above, but also a topic and partition if they aren't impliedby the derived stream's partition.

In some embodiments, an exactly once filter may be implemented based onthe at least once with tag filter. In this embodiment, a receiptacknowledgement message can be saved as reliably as the system (400) cansupport. Additionally, the filter, on receipt of the acknowledgement,could update some persistent record of the delivered cursor. However,persisting this data may be computationally expensive and requiresignificant storage. In an alternative embodiment, given the at leastonce with tag filter, the filter, on a start-up or after a failure, canaccess the output stream and read back a plurality of last-sent messagesin the queue. The filter could then determine the tag of the lastmessage written, then discard any replayed events from the spout untilit was caught up, thus ensuring exactly once delivery.

As described above, many pipelines need to join independently generatedevents to produce a useful result. For example, an ad click event mightbe very lean, with only minimal information about what was clicked. Toget maximum benefit from the click, it must be joined to a previous adserve (or impression) event that has extensive information about whatwas clicked, such as the ad served, who it was served to, and why the adwas picked for this particular ad request.

In batch pipelines, such joins are performed after the close of books(COB) for a batch interval. However, as discussed, this results in joinoperations being performed significantly after the events to join werereceived. Current stream processing techniques suffer from variousdeficiencies in performing joins. In brief, current systems attempt to“simulate” a join by windowing events. However, if events aresufficiently spaced (i.e., outside the join window), joins are notpossible. To maximize speed (i.e., the reason for using a streamprocessor), the join window is generally kept small (in seconds) andthus long periods between events render the joins impossible. Further,in a stream processor, the order of delivery of events isn't guaranteed,and components can't keep a long history of events waiting to be joined.

To remedy these problems, the embodiments provide a pluggable joinframework that may be used in the previously describe systems or otherstreaming processing systems.

FIG. 5 is a block diagram illustrating a pluggable join framework forstream processors according to some embodiments of the disclosure.

As discussed, the streaming system (200) described above guaranteesreliable delivery of events from a low-latency stream processor (304).While providing low-latency outputs, the pipeline (210) has logic todetect lost events and replay them, but also detect and eliminateduplicated events. The results of the pipeline (210) is as reliable ascurrent batch data processing pipelines. To meet these demands, thesystem (200) imposes some additional requirements on joins to supportreliable delivery, primary the ability to resend a secondary event onreceipt of the matching primary when the primary is received long afterthe secondary. The system (500) illustrated in FIG. 5 provides a joinframework plugin that implements the join logic of the pipeline (210),but is agnostic of the details of the events to be joined. In theillustrated embodiment, the system (500) provides a pair of interfacesto handle any event format and a stream processor can use the joinframework plugin to implement a join.

In the illustrated embodiment, a client (502) communicates with a joinframework (504). In the illustrated embodiment, the client (502)comprises a stream processor (or component of a stream processor) thatreceives events and performs join operations on events. In theillustrated embodiment, the join framework (504) comprises a pluggablejoin framework that may be “added on” to the client device. The joinframework (504) receives events from the client (502) and processes joinoperations. The join framework (504) communicates with a backing store(522) via a backing store interface (520). In some embodiments, thebacking store (522) may comprise a distributed database (e.g., Apache®HBase) although other types of data storage systems may be used (e.g.,MySQL, Redis, etc.). In the illustrated embodiment, interface (520)provides an abstraction layer such that the join framework (504) neednot issue commands specific to the backing store (522). The interface(520) handles transferring rows to and from backing store (522). Forexample, in some embodiments, the interface (520) supports a fetch rowand put row command and handles the underlying conversion to commandsrecognizable by the backing store (522).

In the illustrated embodiment, the client (502) includes a processingnode (506), a parent event handler (512) and primary (508) and secondary(510) event interfaces. In one embodiment, the processing node (506)comprises a processing node in a stream topology and may connected toone or more other processing nodes as described above. Processing node(506) may also be referred to as a join node.

In the illustrated embodiment, the interfaces (508, 510, 512) providecallback functions used by the join framework (504) to deal withspecifics of the stream topology events. There are separate interfacesfor handling primary (508) and secondary (510) events, with a commonparent interface (512) that applies to both. The parent interface (512)defines methods that are used for both primary and secondary events. Inone embodiment, the parent interface (512) may implement the followingmethods:

-   -   columnName( )—Return the name of the backing store (522) column        that will store this type of event.    -   getKey(event)—Return the join key for an event. In some        embodiments, the client (502) determines the algorithm for        constructing this key. In one embodiment, the algorithm is        selected to prevent “hot spotting” in the backing store (522).    -   primaryTime(event)—Return the time of the primary event. In some        embodiments, this time is part of the main key. In the        illustrated embodiment, this time may be used to reduce        unnecessary get operations issued to the backing store (522) the        first time a given key value is seen.    -   serialize(event)—Serialize an event into a byte array for        storage in backing store (522).    -   deserialize(serializedEvent)—Deserialize the event that's been        retrieved from backing store (522).    -   failEvent(tag), ackEvent(tag)—If desired, fail or acknowledge an        event received by processing node (506). In some embodiments,        these functions are called once the framework (504) is        completely done processing an event.    -   deliverEvent(tag, event)—Send an event. The tag parameter        identifies the incoming event. In some embodiments, the client        (502) uses the tag for anchoring on emit.

In the illustrated embodiment, the primary handler (508) inherits fromthe parent handler (512) and implements the following event:

-   -   markJoined(primary, secondary, secondaryType):—Mark a primary        event as already joined to a secondary event. In some        embodiments, this is used in the out-of-order case (discussed in        FIGS. 6B and 6C) when the primary event arrives after the        secondary event has already been sent unjoined.

In the illustrated embodiment, the secondary handler (508) inherits fromthe parent handler (512) and implements the following events:

-   -   joinEvent(primary, secondary, late)—Join the primary event and        secondary event and return an annotated secondary event. The        late parameter is true if this the join comprises a late join.    -   markUnjoined(secondary)—Mark this event as unjoined. In some        embodiments, this method is called by the framework (504) when a        primary event can't be found for a secondary event.

In the illustrated embodiment, the join interface (514) and writerthread (518) access the primary and secondary interfaces (508, 510) andissue the above calls during processing of events. Details of thesecalls are provided in further detail in FIGS. 6A, 6B, and 6C.

In the illustrated embodiment, the join interface (514) implements thefollowing methods:

-   -   prepare(context, primaryId, handlerMap)—called to let the        interface (514) initialize itself when the processing node (506)        starts running in a worker thread. In the illustrated        embodiment, the primaryId parameter is the identifier (a        client-defined enumerated type) for the primary event type. In        the illustrated embodiment, the handlerMap parameter comprises a        map from event type to event hander.    -   processPrimary(tag, event)—Process a received primary event. In        one embodiment, the tag is an event tag that will be used in a        subsequent ackEvent( ) failEvent( ) or deliverEvent( ) call.    -   processSecondary(tag, event, type)—Process a secondary event. In        one embodiment, the tag is an event tag that will be used in a        subsequent ackEvent( ) failEvent( ) or deliverEvent( ) call. In        the illustrated embodiment, the type parameter is a parameter        initialized in the call to prepare( ).

In the illustrated embodiment, the join framework (504) includes a RAMcache (516). In one embodiment, the cache (516) comprises a localin-memory cache accessible only within the join framework (504). In oneembodiment, the cache (516) comprises one or more key-value stores orsimilar low-latency caches. In one embodiment, the cache (516) storesevents as value and join keys as keys. As illustrated, the cache (516)may include two logical (and/or physical) caches including dirty cache(526) and delayed cache (524). In one embodiment, the dirty cache (526)stores data to eventually persist to backing store (522). In oneembodiment, the cache (526) comprises a “high watermark” cache. In thisembodiment, the cache (526) knows that any join key created after timeTis still in the cache (526) if that key has been seen at all. In oneembodiment, Tis updated as necessary when the cache (526) is purged. Inthis embodiment, the purging usually eliminates the need for a backingstore (522) fetch the first time a key is seen. In one embodiment, thedelayed cache (524) comprises a cache for temporarily storing eventswhile awaiting a next event. Both caches are described in more detailherein.

In the illustrated embodiment, a writer thread (518) is responsible forreading data from the RAM cache (516) and writing data to the backingstore (522) as required. In the illustrated embodiment, the writerthread (518) may also delivery events to the client (502) via theprimary and secondary event interfaces (508, 510).

FIG. 6A is a flow diagram illustrating a method for performing anin-order join using a pluggable join framework according to someembodiments of the disclosure.

In step 602 a, the method (600 a) receives an event. As discussed, anevent comprises either a primary or secondary event. In general, aprimary event comprises a base event and secondary events compriseevents to be joined to the base event. An example of a primary event isa serve or impression event with details regarding the display of anadvertising creative and a corresponding example of a secondary eventcomprises a click or touch event that refers to a serve or impressionevent and includes minimal data regarding the actual event (e.g., atimestamp). In this example, the joined event could include all fieldsof a serve event and all fields of a corresponding click event, althoughthe specific fields are not limiting. As discussed above, the method(600 a) receives an event via a stream processor. In one embodiment, themethod (600 a) receives events via the processPrimary method callimplemented by the join interface (514) and called by the client (502).

In step 604 a, the method (600 a) determines if one or more secondaryevents are present. In some embodiments, the method (600 a) may query acache to determine if one or more secondary events were already receivedand stored. If secondaries have already been received, the method (600a) can join the events as out-of-order events (step 606 a) and emit thejoined event without further processing. Processing of out-of-orderevents is described more fully in FIGS. 6B and 6C. In some embodiments,the join interface (514) will issue a getKey command to the primaryinterface (508) which returns the join key of the primary event. Thejoin interface (514) will then issue a fetch command to the RAM cache(516) to determine if any secondary events with the same join key existin the RAM cache (516). In some embodiments, the RAM cache (516) mayissue a fetch command to the backing store interface (520) to retrievethe event from the backing store (522).

In step 608 a, if no secondary events were found in step 604 a, themethod (600 a) stores the event in the local cache. In one embodiment,the join interface (514) will insert the primary event into the RAMcache (516) as part of step 608 a.

In step 610 a, the method (600 a) awaits confirmation that the primaryevent was stored in the local cache and then persists the event to thebacking store. In one embodiment, the join interface (514) issues aqueue command to the RAM cache (516) that triggers the write. Once theRAM cache (516) detects that step 608 a was completed, the RAM cache(516) issues a write command to the writer thread (518), the writecommand including the primary event. The writer thread (518) then issuesa put command to the backing store interface (520) to write the primaryevent to the backing store (522).

In step 612 a, the method (600 a) marks the primary event as in-orderand returns the event to the client (502). In one embodiment, since nosecondary events were found, the method (600 a) determines that theprimary event was received before any secondary events and thus theevent was received in-order. In one embodiment, the method (600 a)awaits confirmation that the primary event was written to the backingstore (522) prior to returning the event to the client (502). In oneembodiment, the writer thread (518) delivers the event to the client(502) upon the completed write to the backing store (522). In oneembodiment, the writer thread (518) calls the deliverEvent and ackEventmethods on the primary event handler (508) to deliver the marked event.

In the illustrated embodiment, at a later time, a client (502) receivesa secondary event to be joined with the primary event. In theillustrated embodiment, in step 614 a, the method (600 a) receives thislater secondary event from the client. In one embodiment, the client(502) calls a processSecondary command on the join interface (514) totransmit this event to the method (600 a).

In step 616 a, the method (600 a) fetches the associated primary eventfrom the local cache or backing store, the associated primary eventsharing a join key with the secondary event received in step 614 a. Inone embodiment, the join interface (514) issues a get command to the RAMcache (516) using the join key present in the received secondary event.In some embodiments, if the RAM cache (516) includes a value for thejoin key, the RAM cache (516) returns the event. In some embodiments, ifthe RAM cache (516) does not have a value for the join key, the RAMcache (516) fetches the event from the backing store (522). It should benoted that in FIG. 6B, the method (600 b) determines whether a secondaryevent comprises an in-order or out-of-order event. Thus, in theillustrated embodiment, the method (600 a) will always return a primaryevent in step 616 a barring a catastrophic failure.

In step 618 a, the method (600 a) annotates the secondary event. In oneembodiment, the join interface (514) issues a deserialize command to theprimary event handler (508). The join interface (514) then transmits thedeserialized primary event and the secondary event to the secondaryevent handler (510) via a call to the joinEvent method. In thisembodiment, the join interface (514) will set the late parameter tofalse. In one embodiment, the join interface (514) will then issue acall to the serialize method of the secondary event handler (510) toobtain a serialized version of the joined secondary event.

In step 620 a, the method (600 a) writes the serialized event to thebacking store. In one embodiment, the join interface (514) inserts theserialized secondary event into the RAM cache (516) and instructs theRAM cache (516) to update the backing store (522) upon completingwriting to the dirty cache (526). Once the RAM cache (516) completesinserting the secondary event to the dirty cache (526), the cache (516)transmits the serialized secondary event to the writer thread (518) forwriting to the backing store (522). The writer thread (518) issues theserialized event to the backing store (520) interface which writes theevent to the backing store (522) which will then acknowledgeconfirmation of the write.

In step 622 a, the method (600 a) returns the annotated secondary eventto the client (502). In one embodiment, the method (600 a) marks thesecondary event as “in-order.” In the illustrated embodiment, the method(600 a) delays step 622 a until receiving confirmation that the eventwas written to the backing store (522). In one embodiment, the writerthread (518) calls the deliverEvent and ackEvent methods on thesecondary event handler (510) to deliver the joined secondary event.

In the illustrated embodiment of method (600 a), there may be scenarioswere the secondary event arrives before the primary event has beencommitted to the backing store in step 610 a. In this scenario, theprimary and secondary events will be committed to the backings tore ansent to the client at the same time.

As discussed previously, primary events are always logically createdbefore secondary events. However, there is a possibility that that theprimary event may be received by the client (502) after its relatedsecondary events. In some embodiments, this is caused by the datatransport delivering events. The following methods describe techniquesfor handling out-of-order join events.

FIGS. 6B and 6C are flow diagrams illustrating a method for performingan out-of-order join using a pluggable join framework according to someembodiments of the disclosure.

In step 602 b, the method (600 b) receives an event. As discussed, anevent comprises either a primary or secondary event. In general, aprimary event comprises a base event and secondary events compriseevents to be joined to the base event. An example of a primary event isa serve or impression event with details regarding the display of anadvertising creative and a corresponding example of a secondary eventcomprises a click or touch event that refers to a serve or impressionevent and includes minimal data regarding the actual event (e.g., atimestamp). In this example, the joined event could include all fieldsof a serve event and all fields of a corresponding click event, althoughthe specific fields are not limiting. As discussed above, the method(600 b) receives an event via a stream processor. In one embodiment, themethod (600 b) receives events via the processSecondary method callimplemented by the join interface (514) and called by the client (502).

In step 604 b, the method (600 b) attempts to fetch one or more primaryevents. In one embodiment, the join interface (514) queries the RAMcache (516) using the join key of the secondary event to determine ifany primary events are stored in the dirty cache (526). If no events arestored in the dirty cache (526), the RAM cache (516) may issue a fetchcommand to the backing store interface (520) to retrieve any primaryevents stored in the backing store (522).

In step 606 b, the method (600 b) processes the secondary event receivedin step 602 b as an in-order secondary event upon receiving a primaryevent from the RAM cache (516) or backing store (522). This step isdescribed more fully in FIG. 6A.

In step 608 b, the method (600 b) adds the secondary event to a delayedqueue (524) upon determining that no primary events have been cached orpersisted. In one embodiment, the join interface (512) writes thesecondary event to the delay cache (524) of the RAM cache (526) as partof step 608 b.

In step 610 b, the method (600 b) sets timer and sleeps. In oneembodiment, the sleep timer may be configured based on the needs of thejoin framework (504).

In step 612 b, the method (600 b) determines if a corresponding primaryevent was received while the sleep timer is active.

In step 614 b, the method (600 b) processes the incoming primary eventif the sleep timer did not expire. Details of this processing aredescribed in FIG. 6C. It should be noted that the implementation ofsteps 608 b, 610 b, and 612 b may be optional. In general, these stepscompensate for minimally delayed primaries and short circuit writes tothe cache or backing store if an out-of-order primary event is receivedquickly after a secondary event. Thus, steps 616 b through 624 b mayonly then execute for significantly delayed primary events.

In step 616 b, the method (600 b) removes the secondary event from thedelay queue (524) if the sleep timer expires and no correspondingprimary events were received. In some embodiments, this step may beperformed by a dedicated delay handler executing in the join framework(504). In one embodiment, this handle removes the event from the delayqueue (524) and calls the processSecondary method again to re-processthe event. In this scenario, the method (600 b) will be executed anew,but may proceed directly to step 618 b.

In step 618 b, the method (600 b) marks the secondary event as unjoined.In the illustrated embodiment, the join interface (512) calls themarkUnjoined method of the secondary event handler (510) and passes thesecondary event to the handler (510). The interface (512) may then callthe serialize method on the secondary event handler (510) to receive theserialized event.

In step 620 b, the method (600 b) saves the marked secondary event tothe local cache. In one embodiment, the join interface (514) will insertthe secondary event into the dirty cache (526) of the RAM cache (516) aspart of step 620 b.

In step 622 b, the method (600 b) awaits confirmation that the secondaryevent was stored in the local cache and then persists the event to thebacking store. In one embodiment, the join interface (514) issues aqueue command to the RAM cache (516) that triggers the write. Once theRAM cache (516) detects that step 620 b was completed, the RAM cache(516) issues a write command to the writer thread (518), the writecommand including the secondary event. The writer thread (518) thenissues a put command to the backing store interface (520) to write thesecondary event to the backing store (522).

In step 624 b, the method (600 b) returns the marked secondary event. Inone embodiment, the writer thread (518) delivers the event to the client(502) upon the completed write to the backing store (522). In oneembodiment, the writer thread (518) calls the deliverEvent and ackEventmethods on the secondary event handler (510) to deliver the markedevent.

As discussed above, FIG. 6C is a flow diagram illustrating a method forprocessing an out-of-order primary event according to some embodimentsof the disclosure.

In step 602 c, the method (600 c) receives a primary event. In oneembodiment, the method (600 c) receives events via the processPrimarymethod call implemented by the join interface (514) and called by theclient (502) passing the primary event.

In step 604 c, the method (600 c) queries the backing store using joinkey of the primary event. In some embodiments, the join interface (514)will issue a getKey command to the primary interface (508) which returnsthe join key of the primary event. The join interface (514) will thenissue a fetch command to the RAM cache (516) to determine if anysecondary events with the same join key exist in the RAM cache (516). Insome embodiments, the RAM cache (516) may issue a fetch command to thebacking store interface (520) to retrieve the event from the backingstore (522).

In step 606 c, the method (600 c) determines if any secondary eventswere returned from the query.

In step 608 c, the method (600 c) processes the primary event as anin-order primary if no secondary events are found. In the illustratedembodiment, this processing is performed as described in FIG. 6A.

In step 610 c, the method (600 c) annotates each secondary event withfields from the primary event and marks each secondary event aslate-joined if one or more secondary events were returned from the queryin step 606 c. In one embodiment, the method (600 c) additionally markseach of the primary and secondary events as a “late join.” In oneembodiment, the join interface (514) issues a markJoined command to theprimary event handler (508). The join interface (514) additionallyissues a deserialize command to the secondary event handler (510) foreach identified secondary event. The join interface (514) then transmitsthe deserialized primary event and the secondary event to the secondaryevent handler (510) via a call to the joinEvent method. In thisembodiment, the join interface (514) will set the late parameter totrue.

In step 612 c, the method (600 c) stores the primary event in the localcache. In one embodiment, the join interface (514) will insert theprimary event into the dirty cache (526) of the RAM cache (516) as partof step 612 c.

In step 614 c, the method (600 c) awaits confirmation that the primaryevent was stored in the local cache and then persists the event to thebacking store. In one embodiment, the join interface (514) issues aqueue command to the RAM cache (516) that triggers the write. Once theRAM cache (516) detects that step 614 c was completed, the RAM cache(516) issues a write command to the writer thread (518), the writecommand including the primary event. The writer thread (518) then issuesa put command to the backing store interface (520) to write the primaryevent to the backing store (522).

In step 616 c, the method (600 c) marks all events as out-of-order andreturns each event to the client. In one embodiment, the writer thread(518) delivers the events to the client (502) upon the completed writeto the backing store (522). In one embodiment, the writer thread (518)calls the deliverEvent and ackEvent methods on the primary and secondaryevent handlers (508, 510) to deliver the marked events.

FIG. 7 is a schematic diagram illustrating a computing device showing anexample embodiment of a client or server device used in the variousembodiments of the disclosure.

The computing device (700) may include more or fewer components thanthose shown in FIG. 7. For example, a server computing device may notinclude audio interfaces, displays, keypads, illuminators, hapticinterfaces, GPS receivers, cameras, or sensors.

As shown in the figure, the device (700) includes a processing unit(CPU) (722) in communication with a mass memory (730) via a bus (724).The computing device (700) also includes one or more network interfaces(750), an audio interface (752), a display (754), a keypad (756), anilluminator (758), an input/output interface (760), a haptic interface(762), an optional global positioning systems (GPS) receiver (764) and acamera(s) or other optical, thermal, or electromagnetic sensors (766).Device (700) can include one camera/sensor (766), or a plurality ofcameras/sensors (766), as understood by those of skill in the art. Thepositioning of the camera(s)/sensor(s) (766) on the device (700) canchange per device (700) model, per device (700) capabilities, and thelike, or some combination thereof.

The computing device (700) may optionally communicate with a basestation (not shown), or directly with another computing device. Networkinterface (750) is sometimes known as a transceiver, transceivingdevice, or network interface card (NIC).

The audio interface (752) produces and receives audio signals such asthe sound of a human voice. For example, the audio interface (752) maybe coupled to a speaker and microphone (not shown) to enabletelecommunication with others or generate an audio acknowledgment forsome action. Display (754) may be a liquid crystal display (LCD), gasplasma, light-emitting diode (LED), or any other type of display usedwith a computing device. Display (754) may also include atouch-sensitive screen arranged to receive input from an object such asa stylus or a digit from a human hand.

Keypad (756) may comprise any input device arranged to receive inputfrom a user. Illuminator (758) may provide a status indication orprovide light.

The computing device (700) also comprises input/output interface (760)for communicating with external devices, using communicationtechnologies, such as USB, infrared, Bluetooth™, or the like. The hapticinterface (762) provides tactile feedback to a user of the clientdevice.

Optional GPS transceiver (764) can determine the physical coordinates ofthe computing device (700) on the surface of the Earth, which typicallyoutputs a location as latitude and longitude values. GPS transceiver(764) can also employ other geo-positioning mechanisms, including, butnot limited to, triangulation, assisted GPS (AGPS), E-OTD, CI, SAI, ETA,BSS, or the like, to further determine the physical location of thecomputing device (700) on the surface of the Earth. In one embodiment,however, the computing device (700) may through other components,provide other information that may be employed to determine a physicallocation of the device, including, for example, a MAC address, InternetProtocol (IP) address, or the like.

Mass memory (730) includes a RAM (732), a ROM (734), and other storagemeans. Mass memory (730) illustrates another example of computer storagemedia for storage of information such as computer-readable instructions,data structures, program modules, or other data. Mass memory (730)stores a basic input/output system (“BIOS”) (740) for controlling thelow-level operation of the computing device (700). The mass memory alsostores an operating system (741) for controlling the operation of thecomputing device (700)

Applications (742) may include computer-executable instructions which,when executed by the computing device (700), perform any of the methods(or portions of the methods) described previously in the description ofthe preceding Figures. In some embodiments, the software or programsimplementing the method embodiments can be read from hard disk drive(not illustrated) and temporarily stored in RAM (732) by CPU (722). CPU(722) may then read the software or data from RAM (732), process them,and store them to RAM (732) again.

For this disclosure, a module is a software, hardware, or firmware (orcombination thereof) system, process or functionality, or componentthereof. A module performs or facilitates the processes, features, orfunctions described herein (with or without human interaction oraugmentation). A module can include sub-modules. Software components ofa module may be stored on a computer-readable medium for execution by aprocessor. Modules may be integral to one or more servers or be loadedand executed by one or more servers.

The terms “user,” “subscriber,” “consumer” or “customer” refer to a userof an application or applications as described herein or a consumer ofdata supplied by a data provider. By way of example, and not limitation,the term “user” or “subscriber” can refer to a person who receives dataprovided by the data or service provider over the Internet in a browsersession, or can refer to an automated software application whichreceives the data and stores or processes the data.

One of skill in the art may implement the methods and systems of thepresent disclosure in many manners. As such, the disclosed embodimentsare not to be limited by the preceding exemplary embodiments andexamples. In other words, functional elements being performed by singleor multiple components, in various combinations of hardware and softwareor firmware, and individual functions, may be distributed among softwareapplications at either the client level or server level or both. In thisregard, one may combine any number of the features of the differentembodiments described herein into single or multiple embodiments, andalternate embodiments having fewer than or more than, all the featuresdescribed herein are possible.

Functionality may also be, in whole or in part, distributed amongmultiple components, in manners now known or to become known. Thus,myriad software/hardware/firmware combinations are possible in achievingthe functions, features, interfaces, and preferences described herein.Moreover, the scope of the present disclosure covers conventionallyknown manners for carrying out the described features and functions andinterfaces. The scope of the present disclosure may also covervariations and modifications made to the hardware or software orfirmware components described herein as would be understood by thoseskilled in the art.

Furthermore, the embodiments of methods presented and described asflowcharts in this disclosure are provided by way of example to providea complete understanding of the technology. The disclosed methods arenot limited to the operations and logical flow presented herein.Alternative embodiments exist that alter the order of the variousoperations or include independent sub-operations that are part of a moreextensive operation.

While the disclosure describes various embodiments, such embodimentsshould not limit the teaching of this disclosure to those embodiments.Various changes and modifications may be made to the elements andoperations described above to obtain a result that remains within thescope of the systems and processes described in this disclosure.

What is claimed is:
 1. A method comprising: receiving a first event froma client, the first event comprising a streaming event; determining thatthe first event comprises a primary event; writing the first event to acache and returning the first event to the client; receiving a secondevent from the client, the second event associated with the first event;annotating the second event based on the first event; returning theannotated second event to the client; determining that the eventcomprises a secondary event and that a corresponding primary event wasnot written to the cache; marking the secondary event as un-joined;writing the secondary event to the cache; and returning the markedsecondary event to the client.
 2. The method of claim 1, furthercomprising writing the first event to a backing store after the writingthe first event to the cache.
 3. The method of claim 2, furthercomprising: receiving the corresponding primary event from the client;retrieving the secondary event from the cache; annotating the secondaryevent using the primary event; marking the corresponding primary eventand the secondary event as out-of-order; and returning the correspondingprimary and secondary event to the client.
 4. The method of claim 2,further comprising writing the secondary event to a delay cache andsleeping until receiving the corresponding primary event.
 5. The methodof claim 1, further comprising marking the first event as in-order andreturning the first event to the client before receiving the secondevent.
 6. The method of claim 1, the determining the first eventcomprises a primary event comprising querying the cache for one or moresecondary events.
 7. An apparatus comprising: a processor; and a storagemedium for tangibly storing thereon program logic for execution by theprocessor, the stored program logic causing the processor to perform theoperations of: receiving a first event from a client, the first eventcomprising a streaming event; determining that the first event comprisesa primary event; writing the first event to a cache and returning thefirst event to the client; receiving a second event from the client, thesecond event associated with the first event; annotating the secondevent based on the first event; returning the annotated second event tothe client; determining that the event comprises a secondary event andthat a corresponding primary event was not written to the cache; markingthe secondary event as un-joined; writing the secondary event to thecache; and returning the marked secondary event to the client.
 8. Theapparatus of claim 7, the operations further comprising writing thefirst event to a backing store after the writing the first event to thecache.
 9. The apparatus of claim 7, the operations further comprisingmarking the first event as in-order and returning the first event to theclient before receiving the second event.
 10. The apparatus of claim 7,the determining the first event comprises a primary event comprisingquerying the cache for one or more secondary events.
 11. The apparatusof claim 7, the operations further comprising: receiving thecorresponding primary event from the client; retrieving the secondaryevent from the cache; annotating the secondary event using the primaryevent; marking the corresponding primary event and the secondary eventas out-of-order; and returning the corresponding primary and secondaryevent to the client.
 12. The apparatus of claim 7, the operationsfurther comprising writing the secondary event to a delay cache andsleeping until receiving the corresponding primary event.
 13. Anon-transitory computer-readable storage medium for tangibly storingcomputer program instructions capable of being executed by a computerprocessor, the computer program instructions defining the steps of:receiving a first event from a client, the first event comprising astreaming event; determining that the first event comprises a primaryevent; writing the first event to a cache and returning the first eventto the client; receiving a second event from the client, the secondevent associated with the first event; annotating the second event basedon the first event; returning the annotated second event to the client;determining that the event comprises a secondary event and that acorresponding primary event was not written to the cache; marking thesecondary event as un-joined; writing the secondary event to the cache;and returning the marked secondary event to the client.
 14. Thecomputer-readable storage medium of claim 13, the instructions furtherdefining the step of writing the first event to a backing store afterthe writing the first event to the cache.
 15. The computer-readablestorage medium of claim 13, the instructions further defining the stepof marking the first event as in-order and returning the first event tothe client before receiving the second event.
 16. The computer-readablestorage medium of claim 13, the determining the first event comprises aprimary event comprising querying the cache for one or more secondaryevents.
 17. The computer-readable storage medium of claim 13, theinstructions further defining the steps of: receiving the correspondingprimary event from the client; retrieving the secondary event from thecache; annotating the secondary event using the primary event; markingthe corresponding primary event and the secondary event as out-of-order;and returning the corresponding primary and secondary event to theclient.